Substrate-containing test container for the cultivation and inspection of micro-organisms

ABSTRACT

SUBSTRATE-CONTAINING TEST CONTAINER FOR THE CULTIVATION AND INSPECTION OF MICRO-ORGANISMS COMPRISING A COATING OF SAID SUBSTRATE ON THE INNER SURFACE OF THE SIDE WALLS OF SAID CONTAINER AND AN INSERT MEANS FOR SUPPORTING SAID COATING.

I YH.INGV ORSEN 3,701,717 SUBS'I'RA'TE-CONTAINING TEST CONTAINER FOR THECULTIVATION AND INSPECTION OF MICRO-ORGANISMS Filed Feb. 25, 1970INVENTQR BY 7 I I v ATTORNEY United States Patent 3,701,717SUBSTRATE-CON TAININ G TEST CONTAINER FOR THE CULTIVATION AND INSPECTIONOF MICRO-ORGANISMS Helmuth Ingvorsen, 8 Algade, 4000 Roskilde, DenmarkFiled Feb. 25, 1970, Ser. No. 13,937 Claims priority, application GreatBritain, Feb. 26, 1969, 10,373/ 69; Sept. 5, 1969, 44,127/69 Int. Cl.C12k 1/10 US. Cl. 195-139 1 Claim ABSTRACT OF THE DISCLOSURESubstrate-containing test container for the cultivation and inspectionof micro-organisms comprising a coating of said substrate on the innersurface of the side walls of said container and an insert means forsupporting said coating.

BACKGROUND OF THE INVENTION This invention relates to asubstrate-containing test container and particularly a tubular containerfor the cultivation and inspection of micro-organisms e.g. bacteria orliving cells.

It is well known to cultivate micro-organisms in flat circular dishese.g. Petri dishes, on a substrate such as agar. Suchsubstrate-containing Petri dishes present large surfaces available forcultivation and therefore the micro organisms growing on a substrate insuch Petri dishes can be easily inspected. Therefore, such dishes havefound widespread use in clinics, hospitals etc., in which they are usedfor determining by cultivation the amount and type of bacteria containedin biological fluids. The bacteria cultivated in such Petri dishes arenormally studied and counted by means of a microscope.

However, such substrate-containing Petri dishes are diflicult to pack insuch a manner that they can be sent from one place to another forexample by normal post without the risk of breaking such containersduring transportation.

It has been attempted to use substrate-containing glass tubes which canbe packed in a more satisfactory manner. However, the surface areaavailable for the cultivation of micro-organisms is very small in suchglass tubes compared to that of Petri dishes. In order to increase thefree surface area of the substrate it has been proposed to use tubes inwhich the portion of the glass tube which forms the basis of thesubstrate layer is flat and is disposed at an acute angle to thelongitudinal axis of the tube.

However, such tubes can be manufactured only by using special molds andconsequently, they are more expensive than normal glass tubes.

SUMMARY OF THE INVENTION The object of the invention is to provide asimple and inexpensive substrate-containing container presenting a largefree surface available for the cultivation of microorganisms.

According to the invention there is provided a substrate-containingcontainer having the inner surface of the side walls coated with asubstrate layer.

In a preferred embodiment of the substrate container of the inventionboth the bottom and the side walls are coated with said substrate layer.

The substrate layer may be applied to the inner surface of the containerside walls in several Ways. One of the most simple ways consists inintroducing a liquid substrate into the container and rotating thecontainer about its longitudinal axis. When the fluid substrate has beenuniformly distributed over the inner surface, the container is cooled tosolidify the substrate.

The application of the substrate layer can also be effected byintroducing a liquid substrate in the container and by moving saidcontainer in such a path that the fluid substrate is distributed in aneven layer on the inner surfaces. The container is then cooled tosolidify the substrate.

The substrate layer may also be applied by molding by means of a corewhich is inserted in the container and is removed after thesolidification of the substrate.

Furthermore, the substrate layer may be applied by spraying a warm fluidsubstrate onto the inner surfaces of the container so as to build up auniform layer on said surfaces. The substrate applied may be solidifiedby directing a cooling medium for example a stream of cold air onto theexterior side of the container.

A further method of applying the substrate on the inner surface of atube consists in extruding said layer directly onto said surface.

In some cases and especially when using tubes prepared from plasticmaterials the adherence between the tube walls and the substrate layeris insufficient to prevent the substrate layer from being released fromthe side walls and fall down onto the bottom of the tube. Furthermore,since some micro-organisms liquefy the substrate during their growth ithas been found diflicult to maintain a uniform substrate layer on theside walls during the cultivation.

It has been attempted to eliminate these problems by using tubes havingsmall protrusions or ribs on the inner surface of the side walls.However, the manufacture of tubes having such protrusions or ribs whichserve to improve the bond between the substrate layer and the tube wallshas presented serious problems when the tubes are produced by injectionmoulding. Thus, it is difiicult to remove the mold parts forming saidprotrusions or ribs from the tubes. Therefore, it has been necessary tomanufacture the tubes in two parts and subsequently to weld these twoparts together.

Now it has been found that this complicated production of the tubes canbe avoided by using a perforated insert means to be inserted in saidtubes so as to support the substrate layer applied on the inner surfaceof the side walls.

This insert means may comprise a number of longitudinal ribs which areconnected by spaced transverse ribs so as to form rectangular openings.These ribs are preferably located in such a manner that narrow openingsare formed between the side walls and the exterior sides of said ribs.Thus, when applying a substrate onto the inner surface of the tube theliquid substrate flows into said openings and consequently the substratelayer will be firmly anchored to the insert means, when the liquidsubstrate has been solidified.

In order to facilitate the counting of the microorganisms grown on thesubstrate the area of said openings is for Example 1 cm.

The insert means can be manufactured in one step and consequently nowelding operations are required. After the production of the tubes andthe insert means the latter are inserted in the tubes and a substratelayer is applied onto the inner surface of the side walls of the tube.

The substrate-containing tube is preferably provided with a screw caphaving on its interior side an absorbing pad. This absorbing pad servesto absorb residual liquid present in the substrate-containing tube whena liquid sample, for example urine, has been brought into contact withthe substrate and subsequently has been removed from the tube.

In order to prevent the absorbing pad from being contacted by the liquidsubstrate when distributing said substrate in a uniform layer onto theinner surface of the side walls, the insert means preferably comprisesan inwardly extending collar provided at its upper end. The exteriorside of this collar may be firmly attached to the test tube. In order toobtain an exact mounting of the insert means within the tube the insertmeans preferably also comprises a bottom plate having a diameter whichis equal to that of the tube.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a longitudinal sectionalview of an embodiment of a substrate-containing container according tothe invention,

FIG. 2 shows a side view of a transparent substratecontaining tubeaccordance to the invention,

FIG. 3 shows an enlarged cross sectional view of thesubstrate-containing tube shown in 'FIG. 1, and I FIG. 4 shows anenlarged View of an insert means according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1 a substrate tube 1,e.g. made from glass or a plastic material, comprises a substrate layer2 applied onto the inner surfaces of the side walls and the bottom ofsaid tube.

The substrate tube shown in FIGS. 2 and 3 comprises a plastic tube 3,having a screw cap 4. An insert means 5, shown in detail in FIG. 4 ascomprising a bottom plate 6, vertical ribs 7, transverse ribs 8 and acollar 9, is mounted within said tube 3.

The crossing ribs 7 and 8 form openings 10 which at the lower end of thesubstrate tube are almost quadratic and have an area of 1 cm. The ribs 7and 8 do not contact the inner surface of the side walls andconsequently 4 the liquid substrate medium which is introduced into thetube is permitted to flow in the longitudinal direction as well astransverse thereto so as to form upon cooling a uniform substrate layer11 firmly anchored to said ribs.

The exact position of the insert means 5 Within the tube 3 is controlledby the bottom plate 6 and an annular flange 12.

I claim:

1. A test tube for the cultivation and investigation of micro-organismshaving a film of a solid substrate on the inner surface of the tube, andan insert means within the tube and supporting the substrate film, saidinsert means comprising ribs extending longitudinally of the tube andribs extending transversely thereto and connecting said longitudinallyextending ribs, said ribs being disposed inwardly of the inner surfaceof the tube so as to form narrow spaces between the outer side of theribs and the inner surface of the tube, said insert means furthercomprisinga bottom plate and an annular flange, said plate and flangeextending slightly outwardly of said ribs thereby serving to center saidinsert means in the tube.

References Cited UNITED STATES PATENTS 2,096,866 9/1937 Thompson 23-2593,449,210 6/1969 Rohde 195139 3,532,605 9/1970 Riera 195--139 2,533,03812/1950 Brewer et al. 195--l39 A. LOUIS MONAC-ELL, Primary Examiner R.M. ELLIOTT, Assistant Examiner

